Page:A Voyage of Discovery and Research in the Southern and Antarctic Regions Vol 1.djvu/216

1840 graphical position; but the first observations we obtained here gave us too small a dip by more than two degrees. The cause I of course immediately attributed to local attraction, and directed observations to be made at several different stations. At a position only thirty yards distant from the first station the dip, with the same instrument, was found to be nine degrees less, and therefore eleven degrees in error. The rocks at this point had a peculiar ferruginous appearance, and on presenting some of them to a delicate compass they turned it round and round as swiftly as the hand could move; and moreover were found to possess a powerful degree of polarity, the north and south pole of the fragments depending entirely upon the direction in which they were found lying with reference to the magnetic meridian. They were not however loose stones, as those of a beach, but taken from the laminated rocks of which the land consists, so that we may esteem the whole mass to be one great magnet. Mr. Smith, whom I entrusted with this service, made many observations on various parts of the harbour, all of which are recorded, and will prove an useful lesson to magnetic observers. At the point where we had placed the magnetometers we found the dip accordant with our computations; but this was purely accidental. The dip obtained from observations on board the Erebus, sufficiently removed from the pernicious influence of the land, was that upon which we were obliged to depend, and was pro-